xref: /freebsd/usr.bin/at/at.c (revision b89321a57ddc992e95585bf896d1871fae5b88c1)

/*
 *  at.c : Put file into atrun queue
 *  Copyright (C) 1993, 1994 Thomas Koenig
 *
 *  Atrun & Atq modifications
 *  Copyright (C) 1993  David Parsons
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. The name of the author(s) may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#define _USE_BSD 1

/* System Headers */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#ifndef __FreeBSD__
#include <getopt.h>
#endif

/* Local headers */

#include "at.h"
#include "panic.h"
#include "parsetime.h"
#include "perm.h"

#define MAIN
#include "privs.h"

/* Macros */

#ifndef ATJOB_DIR
#define ATJOB_DIR "/usr/spool/atjobs/"
#endif

#ifndef LFILE
#define LFILE ATJOB_DIR ".lockfile"
#endif

#ifndef ATJOB_MX
#define ATJOB_MX 255
#endif

#define ALARMC 10 /* Number of seconds to wait for timeout */

#define SIZE 255
#define TIMESIZE 50

/* File scope variables */

static char rcsid[] = "$Id: at.c,v 1.2 1994/06/08 18:19:43 kernel Exp $";
char *no_export[] =
{
    "TERM", "TERMCAP", "DISPLAY", "_"
} ;
static send_mail = 0;

/* External variables */

extern char **environ;
int fcreated;
char *namep;
char atfile[] = ATJOB_DIR "12345678901234";

char *atinput = (char*)0;	/* where to get input from */
char atqueue = 0;		/* which queue to examine for jobs (atq) */
char atverify = 0;		/* verify time instead of queuing job */

/* Function declarations */

static void sigc(int signo);
static void alarmc(int signo);
static char *cwdname(void);
static void writefile(time_t runtimer, char queue);
static void list_jobs(void);

/* Signal catching functions */

static void sigc(int signo)
{
/* If the user presses ^C, remove the spool file and exit
 */
    if (fcreated)
    {
	PRIV_START
	    unlink(atfile);
	PRIV_END
    }

    exit(EXIT_FAILURE);
}

static void alarmc(int signo)
{
/* Time out after some seconds
 */
    panic("File locking timed out");
}

/* Local functions */

static char *cwdname(void)
{
/* Read in the current directory; the name will be overwritten on
 * subsequent calls.
 */
    static char *ptr = NULL;
    static size_t size = SIZE;

    if (ptr == NULL)
	ptr = (char *) mymalloc(size);

    while (1)
    {
	if (ptr == NULL)
	    panic("Out of memory");

	if (getcwd(ptr, size-1) != NULL)
	    return ptr;

	if (errno != ERANGE)
	    perr("Cannot get directory");

	free (ptr);
	size += SIZE;
	ptr = (char *) mymalloc(size);
    }
}

static void
writefile(time_t runtimer, char queue)
{
/* This does most of the work if at or batch are invoked for writing a job.
 */
    int i;
    char *ap, *ppos, *mailname;
    struct passwd *pass_entry;
    struct stat statbuf;
    int fdes, lockdes, fd2;
    FILE *fp, *fpin;
    struct sigaction act;
    char **atenv;
    int ch;
    mode_t cmask;
    struct flock lock;

/* Install the signal handler for SIGINT; terminate after removing the
 * spool file if necessary
 */
    act.sa_handler = sigc;
    sigemptyset(&(act.sa_mask));
    act.sa_flags = 0;

    sigaction(SIGINT, &act, NULL);

    ppos = atfile + strlen(ATJOB_DIR);

    /* Loop over all possible file names for running something at this
     * particular time, see if a file is there; the first empty slot at any
     * particular time is used.  Lock the file LFILE first to make sure
     * we're alone when doing this.
     */

    PRIV_START

    if ((lockdes = open(LFILE, O_WRONLY | O_CREAT, S_IWUSR | S_IRUSR)) < 0)
	perr("Cannot open lockfile " LFILE);

    lock.l_type = F_WRLCK; lock.l_whence = SEEK_SET; lock.l_start = 0;
    lock.l_len = 0;

    act.sa_handler = alarmc;
    sigemptyset(&(act.sa_mask));
    act.sa_flags = 0;

    /* Set an alarm so a timeout occurs after ALARMC seconds, in case
     * something is seriously broken.
     */
    sigaction(SIGALRM, &act, NULL);
    alarm(ALARMC);
    fcntl(lockdes, F_SETLKW, &lock);
    alarm(0);

    for(i=0; i<ATJOB_MX; i++)
    {
	sprintf(ppos, "%c%8lx.%2x", queue,
		(unsigned long) (runtimer/60), i);
	for(ap=ppos; *ap != '\0'; ap ++)
	    if (*ap == ' ')
		*ap = '0';

	if (stat(atfile, &statbuf) != 0)
	{
	    if (errno == ENOENT)
		break;
	    else
		perr("Cannot access " ATJOB_DIR);
	}
    }				/* for */

    if (i >= ATJOB_MX)
	panic("Too many jobs already");

    /* Create the file. The x bit is only going to be set after it has
     * been completely written out, to make sure it is not executed in the
     * meantime.  To make sure they do not get deleted, turn off their r
     * bit.  Yes, this is a kluge.
     */
    cmask = umask(S_IRUSR | S_IWUSR | S_IXUSR);
    if ((fdes = creat(atfile, O_WRONLY)) == -1)
	perr("Cannot create atjob file");

    if ((fd2 = dup(fdes)) <0)
	perr("Error in dup() of job file");

    if(fchown(fd2, real_uid, real_gid) != 0)
	perr("Cannot give away file");

    PRIV_END

    /* We no longer need suid root; now we just need to be able to write
     * to the directory, if necessary.
     */

    REDUCE_PRIV(DAEMON_UID, DAEMON_GID)

    /* We've successfully created the file; let's set the flag so it
     * gets removed in case of an interrupt or error.
     */
    fcreated = 1;

    /* Now we can release the lock, so other people can access it
     */
    lock.l_type = F_UNLCK; lock.l_whence = SEEK_SET; lock.l_start = 0;
    lock.l_len = 0;
    fcntl(lockdes, F_SETLKW, &lock);
    close(lockdes);

    if((fp = fdopen(fdes, "w")) == NULL)
	panic("Cannot reopen atjob file");

    /* Get the userid to mail to, first by trying getlogin(), which reads
     * /etc/utmp, then from LOGNAME, finally from getpwuid().
     */
    mailname = getlogin();
    if (mailname == NULL)
	mailname = getenv("LOGNAME");

    if ((mailname == NULL) || (mailname[0] == '\0')
	|| (strlen(mailname) > 8) || (getpwnam(mailname)==NULL))
    {
	pass_entry = getpwuid(getuid());
	if (pass_entry != NULL)
	    mailname = pass_entry->pw_name;
    }

    if (atinput != (char *) NULL)
    {
	fpin = freopen(atinput, "r", stdin);
	if (fpin == NULL)
	    perr("Cannot open input file");
    }
    fprintf(fp, "#! /bin/sh\n# mail %8s %d\n", mailname, send_mail);

    /* Write out the umask at the time of invocation
     */
    fprintf(fp, "umask %lo\n", (unsigned long) cmask);

    /* Write out the environment. Anything that may look like a
     * special character to the shell is quoted, except for \n, which is
     * done with a pair of "'s.  Dont't export the no_export list (such
     * as TERM or DISPLAY) because we don't want these.
     */
    for (atenv= environ; *atenv != NULL; atenv++)
    {
	int export = 1;
	char *eqp;

	eqp = strchr(*atenv, '=');
	if (ap == NULL)
	    eqp = *atenv;
	else
	{
	    int i;
	    for (i=0; i<sizeof(no_export)/sizeof(no_export[0]); i++)
	    {
		export = export
		    && (strncmp(*atenv, no_export[i],
				(size_t) (eqp-*atenv)) != 0);
	    }
	    eqp++;
	}

	if (export)
	{
	    fwrite(*atenv, sizeof(char), eqp-*atenv, fp);
	    for(ap = eqp;*ap != '\0'; ap++)
	    {
		if (*ap == '\n')
		    fprintf(fp, "\"\n\"");
		else
		{
		    if (*ap != '/' && !isalnum(*ap))
			fputc('\\', fp);

		    fputc(*ap, fp);
		}
	    }
	    fputs("; export ", fp);
	    fwrite(*atenv, sizeof(char), eqp-*atenv -1, fp);
	    fputc('\n', fp);

	}
    }
    /* Cd to the directory at the time and write out all the
     * commands the user supplies from stdin.
     */
    fprintf(fp, "cd ");
    for (ap = cwdname(); *ap != '\0'; ap++)
    {
	if (*ap == '\n')
	    fprintf(fp, "\"\n\"");
	else
	{
	    if (*ap != '/' && !isalnum(*ap))
		fputc('\\', fp);

	    fputc(*ap, fp);
	}
    }
    /* Test cd's exit status: die if the original directory has been
     * removed, become unreadable or whatever
     */
    fprintf(fp, " || {\n\t echo 'Execution directory "
	        "inaccessible' >&2\n\t exit 1\n}\n");

    while((ch = getchar()) != EOF)
	fputc(ch, fp);

    fprintf(fp, "\n");
    if (ferror(fp))
	panic("Output error");

    if (ferror(stdin))
	panic("Input error");

    fclose(fp);

    /* Set the x bit so that we're ready to start executing
     */

    if (fchmod(fd2, S_IRUSR | S_IWUSR | S_IXUSR) < 0)
	perr("Cannot give away file");

    close(fd2);
    fprintf(stderr, "Job %s will be executed using /bin/sh\n", ppos);
}

static void
list_jobs()
{
    /* List all a user's jobs in the queue, by looping through ATJOB_DIR,
     * or everybody's if we are root
     */
    struct passwd *pw;
    DIR *spool;
    struct dirent *dirent;
    struct stat buf;
    struct tm runtime;
    unsigned long ctm;
    char queue;
    time_t runtimer;
    char timestr[TIMESIZE];
    int first=1;

    PRIV_START

    if (chdir(ATJOB_DIR) != 0)
	perr("Cannot change to " ATJOB_DIR);

    if ((spool = opendir(".")) == NULL)
	perr("Cannot open " ATJOB_DIR);

    /*	Loop over every file in the directory
     */
    while((dirent = readdir(spool)) != NULL) {
	if (stat(dirent->d_name, &buf) != 0)
	    perr("Cannot stat in " ATJOB_DIR);

	/* See it's a regular file and has its x bit turned on and
         * is the user's
         */
	if (!S_ISREG(buf.st_mode)
	    || ((buf.st_uid != real_uid) && ! (real_uid == 0))
	    || !(S_IXUSR & buf.st_mode || atverify))
	    continue;

	if(sscanf(dirent->d_name, "%c%8lx", &queue, &ctm)!=2)
	    continue;

	if (atqueue && (queue != atqueue))
	    continue;

	runtimer = 60*(time_t) ctm;
	runtime = *localtime(&runtimer);
	strftime(timestr, TIMESIZE, "%X %x", &runtime);
	if (first) {
	    printf("Date\t\t\tOwner\tQueue\tJob#\n");
	    first=0;
	}
	pw = getpwuid(buf.st_uid);

	printf("%s\t%s\t%c%s\t%s\n",
	       timestr,
	       pw ? pw->pw_name : "???",
	       queue,
	       (S_IXUSR & buf.st_mode) ? "":"(done)",
	       dirent->d_name);
    }
    PRIV_END
}

static void
delete_jobs(int argc, char **argv)
{
    /* Delete every argument (job - ID) given
     */
    int i;
    struct stat buf;

    PRIV_START

    if (chdir(ATJOB_DIR) != 0)
	perr("Cannot change to " ATJOB_DIR);

    for (i=optind; i < argc; i++) {
	if (stat(argv[i], &buf) != 0)
	    perr(argv[i]);
	if ((buf.st_uid != real_uid) && !(real_uid == 0)) {
	    fprintf(stderr, "%s: Not owner\n", argv[i]);
	    exit(EXIT_FAILURE);
	}
	if (unlink(argv[i]) != 0)
	    perr(argv[i]);
    }
    PRIV_END
} /* delete_jobs */

/* Global functions */

void *
mymalloc(size_t n)
{
    void *p;
    if ((p=malloc(n))==(void *)0)
    {
	fprintf(stderr,"Virtual memory exhausted\n");
	exit(EXIT_FAILURE);
    }
    return p;
}

int
main(int argc, char **argv)
{
    int c;
    char queue = DEFAULT_AT_QUEUE;
    char queue_set = 0;
    char *pgm;

    enum { ATQ, ATRM, AT, BATCH };	/* what program we want to run */
    int program = AT;			/* our default program */
    char *options = "q:f:mvldbV";	/* default options for at */
    int disp_version = 0;
    time_t timer;

    RELINQUISH_PRIVS

    /* Eat any leading paths
     */
    if ((pgm = strrchr(argv[0], '/')) == NULL)
	pgm = argv[0];
    else
        pgm++;

    namep = pgm;

    /* find out what this program is supposed to do
     */
    if (strcmp(pgm, "atq") == 0) {
	program = ATQ;
	options = "q:vV";
    }
    else if (strcmp(pgm, "atrm") == 0) {
	program = ATRM;
	options = "V";
    }
    else if (strcmp(pgm, "batch") == 0) {
	program = BATCH;
	options = "f:q:mvV";
    }

    /* process whatever options we can process
     */
    opterr=1;
    while ((c=getopt(argc, argv, options)) != EOF)
	switch (c) {
	case 'v':   /* verify time settings */
	    atverify = 1;
	    break;

	case 'm':   /* send mail when job is complete */
	    send_mail = 1;
	    break;

	case 'f':
	    atinput = optarg;
	    break;

	case 'q':    /* specify queue */
	    if (strlen(optarg) > 1)
		usage();

	    atqueue = queue = *optarg;
	    if (!(islower(queue)||isupper(queue)))
		usage();

	    queue_set = 1;
	    break;

	case 'd':
	    if (program != AT)
		usage();

	    program = ATRM;
	    options = "V";
	    break;

	case 'l':
	    if (program != AT)
		usage();

	    program = ATQ;
	    options = "q:vV";
	    break;

	case 'b':
	    if (program != AT)
		usage();

	    program = BATCH;
	    options = "f:q:mvV";
	    break;

	case 'V':
	    disp_version = 1;
	    break;

	default:
	    usage();
	    break;
	}
    /* end of options eating
     */

    if (disp_version)
	fprintf(stderr, "at version " VERSION "\n"
			"Bug reports to: ig25@rz.uni-karlsruhe.de (Thomas Koenig)\n");

    /* select our program
     */
    if(!check_permission())
    {
	fprintf(stderr, "You do not have permission to use %s.\n",namep);
	exit(EXIT_FAILURE);
    }
    switch (program) {
    case ATQ:

	REDUCE_PRIV(DAEMON_UID, DAEMON_GID)

	list_jobs();
	break;

    case ATRM:

	REDUCE_PRIV(DAEMON_UID, DAEMON_GID)

	delete_jobs(argc, argv);
	break;

    case AT:
	timer = parsetime(argc, argv);
	if (atverify)
	{
	    struct tm *tm = localtime(&timer);
	    fprintf(stderr, "%s\n", asctime(tm));
	}
	writefile(timer, queue);
	break;

    case BATCH:
	if (queue_set)
	    queue = toupper(queue);
	else
	    queue = DEFAULT_BATCH_QUEUE;

	if (argc > optind)
	    timer = parsetime(argc, argv);
	else
	    timer = time(NULL);

	if (atverify)
	{
	    struct tm *tm = localtime(&timer);
	    fprintf(stderr, "%s\n", asctime(tm));
	}

        writefile(timer, queue);
	break;

    default:
	panic("Internal error");
	break;
    }
    exit(EXIT_SUCCESS);
}